What if there was a minimally invasive alternative to skin biopsies for detecting disease biomarkers in patients with psoriasis? Findings from recently published research in Journal of Allergy and Clinical Immunology suggest that tape strips, subjected to RNA sequencing, can detect distinct immune and barrier signatures in both lesional and nonlesional psoriasis and atopic dermatitis (AD) skin.
The study included tape strips obtained from lesional and nonlesional skin of patients with AD, psoriasis and healthy controls. Ultimately, the goal was to “construct a global transcriptome of tape strips from lesional and nonlesional skin of adults with moderate-to-severe AD and psoriasis.”  Using RNA sequencing, researchers completed the first molecular profiling to fully characterize and compare AD and psoriasis. The authors note that it is also the “most comprehensive tape strip molecular profiling in any inflammatory skin disease to date.”1 By RNA-seq measuring of transcripts and targeted qRT-PCR analysis of biomarkers, researchers successfully defined a cutaneous molecular phenotype of psoriasis.
“Sometimes, patients will need a biopsy to differentiate between AD and psoriasis. And its vital to make that determination because the treatment for each is diagnosis dependent. Biopsies are invasive though, so its important to be able to differentiate between these diseases in a noninvasive way,” says Dr. Emma Guttman-Yassky, who is the Sol and Clara Kest Professor and Vice Chair for Research at the Department of Dermatology (incoming Chair in January 2021), Director of the Center for Excellence in Eczema, and Director of the Laboratory of Inflammatory Skin Diseases at the Icahn School of Medicine at Mount Sinai Medical Center, New York.
Established findings from molecular studies of skin biopsy samples have shown that psoriasis is primarily TH17/IL-23–polarized. Consistent with biopsy findings, tape strip samples from patients with psoriasis showed prominent and significant TH17/TH1 upregulation characterized lesional and nonlesional skin, differing from tape-stripped skin of patients with AD. Data also showed that tape strips from patients with psoriasis had significant upregulation of IL-17-related biomarkers, compared with skin from patients with AD and healthy skin.
Furthermore, while data found terminal differentiation, tight junction, and levels of late cornified envelope (LCE) products were abnormal in both AD and psoriasis, the levels of expression of LCE3 gene products were increased in psoriasis but not in AD.
Interestingly, data findings identified the nitric oxide synthase 2 (NOS2)/inducible nitric oxide synthase (iNOS) biomarker as a “perfect discriminator” between psoriasis and AD. From the study paper “quantification of NOS2/iNOS in tape strips can potentially help diagnose psoriasis in clinically ambiguous cases or to track treatment response.”1
Biopsies can cause scarring, pain, and have a risk of infection; this can limit their use in longitudinal studies and larger clinical trials. Tape strips, due to their use of an adhesive film, carry less risk, making them a potential minimally invasive alternative to skin biopsies for tracking disease activity. “This is exciting because patients don’t like biopsies. They’re painful and can cause scarring. But with tape strips, everyone will say, ‘yes.’ They don’t cause scarring or sequelae,” Dr. Guttman-Yassky says. “Tape strips may open new avenues of research that weren’t available before. For instance, we can’t biopsy the skin of children so we can’t look for biomarkers. Tape strips would allow for that, which would be great for our pediatric patients.”
While tape-stripping has its limitations (such as how time consuming the RNA isolation process is), its ability to accurately discriminate between AD and psoriasis and be less invasive than biopsies may make it more advantageous for future longitudinal studies and clinical trials.
 He H, Bissonnette R, Wu J, et al. Tape strips detect distinct immune and barrier profiles in atopic dermatitis and psoriasis. J Allergy Clin Immunol. 2020 Jul 9;S0091-6749(20)30824-1. doi: 10.1016/j.jaci.2020.05.048.